Internal Fixer For Anchor Having Releasable Tensioning Steel Wire

ABSTRACT

The present invention provides an internal fixer for an anchor having a releasable tensioning steel wire. The internal fixer of the present invention includes a first outer body ( 10 ), which is provided with a tube coupling hole ( 11 ), a body seating hole ( 13 ) and a wedge receiving body support means; and a wedge receiving body ( 30 ), which is seated in the body seating hole ( 13 ) and has a conical wedge seating hole ( 31 ), into which separated wedge bodies ( 41 ) are seated. The internal fixer further includes a wedge unit ( 40 ), which is seated in the wedge seating hole ( 31 ) of the wedge receiving body ( 30 ) and comprises the three separated wedge bodies ( 41 ); and a second outer body ( 20 ), which supports and covers both the wedge receiving body ( 30 ), which is seated in the body seating hole ( 13 ), and the wedge unit ( 40 ), which is placed in the wedge seating hole ( 31 ).

TECHNICAL FIELD

The present invention relates, in general, to internal fixers foranchors having releasable tensioning steel wires and, more particularly,to an internal fixer for an anchor having a releasable tensioning steelwire in which, when the tensioning steel wire is tensioned, a wedgereceiving body along with separated wedge bodies is moved in thedirection in which the tensioning steel wire is tensioned, and isfastened, so that the space required for movement of a wedge unit whenthe tensile force is removed is ensured, and in which only the separatedwedge bodies are moved backwards by repulsive force generated when thetensile force is removing from the tensioning steel wire in the fixedstate of the wedge receiving body, or by both the force of striking thetensioning steel wire inwards and the restoring force of a spring, andthey are separated in the diameter direction, so that the tensioningsteel wire can be easily and reliably removed.

BACKGROUND ART

Generally, ground anchors are used in engineering work such as bracingwork and engineering work for stabilizing a tunnel portal or forreinforcing a stone wall or a retaining wall. For construction of aground anchor, a hole is bored at a desired position in soft groundusing a boring machine, and a grout hose and a load-carrying body, whichincludes the tensioning steel wire and the internal fixer, are insertedinto the boring hole, before grout is injected through the grout hose.After the injected grout cures with the load-carrying body, an externalfixer is coupled to the other end of the tensioning steel wire.Thereafter, the tensioning steel wire is pulled by a tensioning machine,so that the grout and ground are tensioned, thus reinforcing the softground.

Such a ground anchor has advantages of efficient construction managementwhen working in urban areas and reduction in construction period.However, in the case that other engineering work is being conductedadjacent to the area in which the ground anchor is installed, becausethe tensioning steel wire has six times the strength of a typical steelwire per unit area, an excavator and a boring machine may be damaged,and the construction period may be increased. To solve theabove-mentioned problem, a ground anchor, which has a structure suchthat a tensioning steel wire is removable depending on the constructionprocess after excavation work has been completed, was developed.

Various internal fixers for anchors having releasable tensioning steelwires have been proposed. Of them, two will be explained herein below.First, in a technique proposed in Korean Patent Registration No.10-0447967, which was filed by the inventor of the present invention, awedge unit is elastically supported by a spring in a wedge unitinstallation space of an anchor body, and a tensioning steel wire isinserted into and held by the wedge unit. In this technique, a process,in which the tensioning steel wire is instantaneously moved backwardsand released by striking a strand or strands of the tensioning steelwire and, simultaneously, after the strand of the tensioning steel wireis inserted, the tensioning steel wire is held while the wedge unit isinserted into the wedge unit installation space by the elasticity of thespring, is repeated several times. Thus, at the moment at which an endof the tensioning steel wire other than the struck strand escapes fromthe wedge unit, the tensioning steel wire is released. Thereafter, thetensioning steel wire is pulled out, thus being removed.

Furthermore, in an internal fixer for an anchor having a releasabletensioning steel wire in Korean Utility Model Registration No.20-0309952, a tensioning steel wire is inserted into a main body untilit reaches separated wedge bodies and a repulsive force transmission capthrough a coned disc spring and a wedge receiving body.

Furthermore, an elastic spring, which is provided on the upper end ofthe repulsive force transmission cap, is locked to a support stop of acover cap. The wedge receiving body is elastically installed in the mainbody. The separated wedge bodies are seated in the wedge receiving body.

In the internal fixer of the above Korean Utility Model having theabove-mentioned construction, when the tensioning steel wire istensioned, the repulsive force transmission cap and the wedge receivingbody, which are coupled to the separated wedge bodies, are moved alongwith the separated wedge bodies in the direction in which the tensioningsteel wire is tensioned, and the coned disc spring is compressed.Thereafter, when the tensioning steel wire is cut, the repulsive forcetransmission cap and the separated wedge bodies are moved by therepulsive force. Then, the elastic spring of the repulsive forcetransmission cap is locked to a locking groove of the cover cap. At thisposition, because the separated wedge bodies are in a state of beingslightly removed from the wedge receiving body, the separated wedgebodies are separated in the diameter direction, so that the tensioningsteel wire may be removed by pulling.

DISCLOSURE OF INVENTION Technical Problem

In the internal fixer disclosed in Korean Patent Registration No.10-0447967, which was filed by the inventor of the present invention,because the tensioning steel wire is pushed out and removed by strikingand inserting a strand and strands of the tensioning steel wire, thetensioning steel wire can be reliably removed even if the anchor head,which is the internal fixer, rusts due to water that permeates theanchor head. However, because the number of times a strand of thetensioning steel wire must be struck typically reaches several tens oftimes, work efficiency is reduced. As well, there is a problem in that,since physical fatigue increases as the work progresses, a worker mayfail to carry out the work.

Meanwhile, in the internal fixer disclosed in Korean Utility ModelRegistration No. 20-0309952, the repulsive force transmission cap andthe separated wedge bodies are moved by repulsive force generated whencutting the tensioning steel wire, thereby the wedge receiving body ismoved in the same direction. Therefore, expansion of the separated wedgebodies is unreliable. To solve this, the length of the main body isincreased, and thus there is a problem of increased material cost.

In particular, because a process of cutting the tensioning steel wire istypically conducted using an oxygen cutting machine, the strands of thetensioning steel wire are consecutively cut one by one or in groups oftwo, but not all at the same time. Thus, the repulsive force of thetensioning steel wire is generated slowly. Therefore, this repulsiveforce may not be enough for the elastic spring, which is provided on theupper end of the repulsive force transmission cap, to reach the lockinggroove of the cover cap. In this case, the elastic spring, which isprovided on the upper end of the repulsive force transmission cap, isnot locked to the locking groove of the cover cap, so that the separatedwedge bodies remain in the wedge receiving body without expanding indiameter. As a result, the tensioning steel wire might not be removed.

Technical Solution

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the prior art, and objects of the presentinvention will be presented herein below.

A first object of the present invention is to provide an internal fixerfor an anchor having a releasable tensioning steel wire in which, whenthe tensioning steel wire is tensioned after the internal fixer isinstalled in the ground, a wedge receiving body along with a wedge unitis moved in the direction in which the tensioning steel wire istensioned, and is fastened, so that the space required for movement of awedge unit when the tensile force is removed is reliably ensured, and inwhich only the separated wedge bodies are moved backwards by repulsiveforce generated when removing the tensile force from the tensioningsteel wire when the wedge receiving body is in a fixed state, or by theforce of striking the tensioning steel wire inwards, and they areexpanded in diameter, so that the tensioning steel wire can be easilyand reliably removed.

A second object of the present invention is to provide an internal fixerin which a wedge returning member is additionally provided at a lowerposition in a body receiving hole of a first outer body, so that, whenthe tensioning steel wire is cut to remove it after having beentensioned, the wedge returning member pushes the wedge unit backwardsfrom the wedge seating hole of the wedge receiving body, thus theseparated wedge bodies of the wedge unit are separated in the diameterdirection, thereby the tensioning steel wire is easily released.

A third object of the present invention is to provide an internal fixer,in which, when the tensioning steel wire is inserted into the internalfixer, the separated wedge bodies are pushed backwards from the wedgeseating hole of the wedge receiving body and expand in diameter, so thatthe end of the tensioning steel wire is inserted into the separatedwedge bodies and, thereafter, when the force that has been applied tothe tensioning steel wire is removed, the separated wedge bodies areinserted into the wedge seating hole of the wedge receiving body by therestoring force of the elastic support member, so that the tensioningsteel wire can be easily held by the wedge unit, that is, the assemblyof the tensioning steel wire can be easily realized merely by insertingand releasing the tensioning steel wire.

A fourth object of the present invention is to provide an internal fixerin which a cap member, which protrudes from the upper end of the wedgeunit, is provided, so that, because the elastic support member is seatedonto the wedge unit and is fitted over the outer surface of the capmember, operational precision is ensured and the elastic support memberdoes not become misaligned or undesirably move, and, as well, the end ofthe tensioning steel wire, which is inserted through a tube couplinghole of the first outer body, is inserted into the cap member via theseparated wedge bodies, so that the tensioning steel wire is reliablyheld by the separated wedge bodies, and, as the separated wedge bodieshold the tensioning steel wire more strongly, the part of the tensioningsteel wire that is in the cap member becomes untwisted, thus thediameter of that part of the tensioning steel wire is slightlyincreased, thereby the tensioning steel wire can be more securely held,as if a stop protrusion were formed on the tensioning steel wire.

A fifth object of the present invention is to provide an internal fixerin which the elastic support member and the wedge returning memberrespectively comprise a compression coil spring which is fitted over thecap member protruding from the upper end of the wedge unit, and acompression coil spring which supports the lower end of the separatedwedge bodies of the wedge unit, so that the number of elements isminimized, thus reducing the manufacturing cost, and enhancingworkability.

Advantageous Effect

In the internal fixer for an anchor having a releasable tensioning steelwire according to the present invention, when the tensioning steel wireis tensioned after the internal fixer has been installed in the ground,a wedge receiving body along with a wedge unit is moved in thedirection, in which the tensioning steel wire is tensioned, and isfastened, so that the space required for movement of a wedge unit whenthe tensile force is removed is reliably ensured. Furthermore, only theseparated wedge bodies are moved backwards and expanded in diameter byrepulsive force generated when the tensile force of the tensioning steelwire is removed when the wedge receiving body is in a fixed state, or bythe force of striking the tensioning steel wire inwards, so that thetensioning steel wire can be easily and reliably removed.

As well, a wedge returning member is additionally provided at a lowerposition in a body receiving hole of a first outer body, so that, whenthe tensioning steel wire is cut to remove it after having beentensioned, the wedge returning member pushes the wedge unit backwardsfrom the wedge seating hole of the wedge receiving body, thus theseparated wedge bodies of the wedge unit are separated in a diameterdirection, thereby the tensioning steel wire is easily released.

In addition, when the tensioning steel wire is inserted into theinternal fixer, the separated wedge bodies are pushed backwards from thewedge seating hole of the wedge receiving body and expanded in diameter,so that the end of the tensioning steel wire is inserted into theseparated wedge bodies and, thereafter, when the force that has beenapplied to the tensioning steel wire is removed, the separated wedgebodies are inserted into the wedge seating hole of the wedge receivingbody by the restoring force of the elastic support member, so that thetensioning steel wire can be easily held by the wedge unit. In otherwords, the assembly of the tensioning steel wire can be easily realizedmerely by inserting and releasing the tensioning steel wire.

Moreover, a cap member, which protrudes from the upper end of the wedgeunit, is provided, so that, because the elastic support member is seatedonto the wedge unit and fitted over the outer surface of the cap member,operational precision is ensured and the elastic support member does notbecome misaligned or undesirably move. As well, the end of thetensioning steel wire, which is inserted through a tube coupling hole ofthe first outer body, is inserted into the cap member via the separatedwedge bodies, so that the tensioning steel wire is reliably held by theseparated wedge bodies, and, as the separated wedge bodies hold thetensioning steel wire more strongly, the part of the tensioning steelwire that is in the cap member becomes untwisted, thus the diameter ofthat part of the tensioning steel wire is slightly increased, therebythe tensioning steel wire can be held more securely, as if a stopprotrusion were formed on the tensioning steel wire.

Finally, the elastic support member and the wedge returning memberrespectively comprise a compression coil spring, which is fitted overthe cap member protruding from the upper end of the wedge unit, and acompression coil spring, which supports the lower end of the separatedwedge bodies of the wedge unit, so that the number of elements isminimized, thus reducing the manufacturing cost and enhancingworkability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing an internal fixer for an anchorhaving a releasable tensioning steel wire, according to an embodiment ofthe present invention;

FIG. 2 is an exploded perspective view of FIG. 1;

FIG. 3 is a sectional view showing the tensioning steel wire in a stateof being tensioned in the internal fixer according to the presentinvention;

FIG. 4 is a sectional view showing the tensioning steel wire releasedfrom a wedge unit in the internal fixer according to the presentinvention;

FIGS. 5 through 11 are views showing embodiments of a wedge receivingbody support means of the internal fixer according to the presentinvention;

FIG. 12 is a sectional view showing an internal fixer for an anchorhaving a releasable tensioning steel wire, a wedge returning means beingprovided for a wedge unit, according to another embodiment of thepresent invention;

FIGS. 13 through 15 are views illustrating processes in which thetensioning steel wire is held by the internal fixer, tensioned, andreleased from the internal fixer according to present invention;

FIG. 16 is a sectional view showing an internal fixer for an anchorhaving a releasable tensioning steel wire, a wedge returning means beingprovided in a wedge unit, according to another embodiment of the presentinvention; and

FIGS. 17 through 19 are views showing internal fixers for anchors havingreleasable tensioning steel wires, a wedge support means being providedin wedge units, according to another embodiment of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

In order to accomplish the above objects, the present invention providesan internal fixer for an anchor having a releasable tensioning steelwire, including: a first outer body, with a tube coupling hole and abody seating hole coaxially formed in the first outer body so that thetensioning steel wire passes therethrough, and a wedge receiving bodysupport means provided on an inner surface of the body seating hole; awedge receiving body seated by the wedge receiving body support means inthe body seating hole and having a conical wedge seating hole, intowhich separated wedge bodies are seated; a wedge unit seated into thewedge seating hole of the wedge receiving body and comprising the threeseparated wedge bodies, which are arranged in a cone shape to hold thetensioning steel wire; and a second outer body supporting and coveringthe wedge receiving body, which is seated in the body seating hole ofthe first outer body, and the wedge unit, which is placed in the wedgeseating hole of the wedge receiving body.

The second outer body has a shape such that it supports and covers thewedge receiving body, which is seated in the body seating hole of thefirst outer body, and an elastic support member is provided in thesecond outer body and elastically supports, pushes and seats the wedgeunit, which is placed in the wedge seating hole of the wedge receivingbody, into the wedge seating hole.

In the internal fixer for the anchor having the releasable tensioningsteel wire according to the present invention, it is sufficient if thewedge receiving body support means of the first outer body has astructure such that, when tensile force is applied to the tensioningsteel wire, the wedge receiving body is advanced along with the wedgeunit and fastened to the bottom of the body seating hole.

The wedge receiving body support means may comprise a supportprotrusion, which protrudes from the inner surface of the body seatinghole. The support protrusion may have a ring shape, which is formedaround the entire circumference of the body seating hole, or,alternatively, may comprise a plurality of support protrusions, whichare spaced apart from each other. The support protrusion may havevarious shapes, such as a rounded cross-section, a rectangularcross-section or a trapezoidal cross-section.

Furthermore, the wedge receiving body support means may be realized by atapered inner surface of the body seating hole which is reduced indiameter from a deep portion thereof to a shallow portion thereof.

The wedge receiving body support means may comprise at least one supportO-ring or expandable C-shaped metal ring, which is provided in a ringgroove formed in the inner surface of the body seating hole, such that,when the wedge receiving body is advanced by the tensioning steel wire,it comes into close contact with and holds the outer surface of thewedge receiving body. In the case that the C-shaped metal ring is used,a ring stop groove may be formed in the inner surface of the wedgeseating groove, so that, when the wedge receiving body is advanced bythe tensioning steel sire, the C-shaped metal ring is locked to the ringstop groove.

As well, a C-shaped metal ring may be provided on the outer surface ofthe wedge receiving body. In this case, a ring stop groove is formed inthe inner surface of the body seating hole.

The internal fixer for the anchor having the releasable tensioning steelwire according to the present invention may further include a wedgereturning member, which is provided in the body seating hole of thefirst outer body, so that, when the wedge receiving body along with thewedge unit is advanced and fastened to the body seating hole, the wedgeunit, which is placed in the wedge seating hole of the wedge receivingbody, is biased backwards by the wedge returning member.

The wedge returning member suffices as a compression coil spring. A ringmember, which has a flange on an end thereof, may be provided on an endof the wedge returning member to support lower ends of the separatedwedge bodies.

The wedge returning member may comprise a spring seating hole, which isformed in the bottom of the body seating hole for installation of thewedge returning member, and a support protrusion, which is provided onthe bottom of the spring seating hole to hold the end of the wedgereturning member.

In the internal fixer for the anchor having the releasable tensioningsteel wire according to the present invention, the elastic supportmember may be provided in the second outer body to elastically push andseat the wedge unit into the wedge seating hole of the wedge receivingbody. The elastic support member suffices as a compression coil spring.A cap member may be provided in an inner ring groove, which is formed inupper ends of the separated wedge bodies constituting the wedge unit, sothat an elastic support member is fitted over the cap member and thetensioning steel wire is more deeply inserted into the cap member.

Furthermore, a compression cover may be provided on the separated wedgebodies outside the cap member between the separated wedge bodies and theelastic support member to ensure reliable expansion of the separatedwedge bodies.

MODE FOR THE INVENTION

Hereinafter, an internal fixer for an anchor having a releasabletensioning steel wire according to the present invention will bedescribed in detail with reference to the attached drawings.

FIG. 1 is a sectional view showing the internal fixer for the anchorhaving the releasable tensioning steel wire, according to an embodimentof the present invention. FIG. 2 is an exploded perspective view of FIG.1.

As shown in the drawings, in the internal fixer for the anchor havingthe releasable tensioning steel wire according to the present invention,a wedge receiving body 30 is installed in first and second outer bodies10 and 20, and a wedge unit 40 is inserted into the wedge receiving body30 and is supported by the second outer body 20 such that the wedge unit40 is prevented from being undesirably removed from the wedge receivingbody 30. The wedge unit 40 has a structure such that, when thereleasable tensioning steel wire 30 is inserted into the wedge unit 40through a tube coupling hole 11 of the first outer body 10, the wedgeunit 40 holds the tensioning steel wire 30. Typically, the tensioningsteel wire 30 comprises seven strands of steel wires, in which sixstrands of steel wires are twisted around a center steel wire at aregular pitch.

The first outer body 10 has the tube coupling hole 11, through which thetensioning steel wire 30 is inserted, and a body seating hole 13, whichis coaxially formed therein, and in which the wedge receiving body 30 isseated. Furthermore, a support protrusion 13 a, which is a means forsupporting the wedge receiving body 30, is provided on thecircumferential inner surface of the body seating hole 13, so that,while no tension is applied to the tensioning steel wire 50, the wedgereceiving body 30 is seated at a rear position of the first outer body10 and is supported by both the support protrusion 13 a and the secondouter body 20, and, when tensile force for pulling the tensioning steelwire 50 is applied to the tensioning steel wire 50 after the internalfixer has been installed in the ground, the support protrusion 13 aallows the wedge receiving body 30 along with the wedge unit 40 to bemoved towards the tube coupling hole 11 (that is, to advance forwards).

Preferably, the support protrusion 13 a protrudes from the inner surfaceof the body seating hole 13 to a height ranging from 0.1 mm to 0.5 mm.The reason why the height of the support protrusion 13 a is limited isthat, if the protruding height is less than 0.1 mm, the supportprotrusion 13 a may be easily destroyed even by a relatively weaktensioning load applied to the tensioning steel wire 50, and thus thesupport protrusion 13 a cannot conduct its intended function, and,conversely, if the height to which the support protrusion 13 a protrudesis 0.5 mm or more, because a very large outer force is required todestroy the support protrusion 13 a, a tensioning machine having a largecapacity is required and, as well, when the wedge receiving body 30 isadvanced, a large impact is applied to the first outer body 10, and thisimpact may have a bad influence on the internal fixer.

In this embodiment, the support protrusion 13 a, which protrudesthroughout the entire circumference of the circumferential inner surfaceof the body seating hole 13 to have a ring shape and to form an angledand stepped part, is used as the wedge receiving body support means.Furthermore, the support protrusion 13 a may have a roundedcross-section, a rectangular cross-section or a trapezoidalcross-section. As well, a plurality of support protrusions, which arespaced apart from each other on the circumferential inner surface of thebody seating hole 13, may be used as the wedge receiving body supportmeans. In addition, the wedge receiving body support means may berealized by a support protrusion that has two or more steps. Inparticular, as shown in FIG. 5, the wedge receiving body support meansmay be realized by a tapered inner surface of the body seating hole 13which is reduced in diameter from the rear portion to the front portion.

In addition, the wedge receiving body support means may be provided onlyon the circumferential inner surface of the body seating hole, or,alternatively, may be provided in a combined manner both on the wedgereceiving body and on the circumferential inner surface of the bodyseating hole. Hereinafter, examples thereof will be described.

FIG. 16 shows at least one support O-ring 14, which is provided in aring seating groove 13 b in the circumferential inner surface of a bodyseating hole 13 so that, when a wedge receiving body 30 is advanced bypulling the tensioning steel wire 60, the support O-ring 14, which hassupported one end of the wedge receiving body 30, comes into closecontact with and holds the circumferential outer surface of the wedgereceiving body 30.

FIGS. 7 and 8 show a C-shaped metal ring 15, which elastically expandsin diameter and is provided in a ring seating groove 13 b in thecircumferential inner surface of a body seating hole 13 so that, when awedge receiving body 30 is advanced by pulling the tensioning steel wire60, the C-shaped metal ring 15, which has supported an end of the wedgereceiving body 30, holds the circumferential outer surface of the wedgereceiving body 30.

FIGS. 9 and 10 show a C-shaped metal ring 15, which elastically expandsin diameter and in the circumferential inner surface of a body seatinghole 13 to temporarily support the end of a wedge receiving body 30, andshow a ring stop groove 32, which is formed in the circumferential outersurface of the wedge receiving body 30 such that, when the wedgereceiving body 30 is pulled out by the tensioning steel wire 50, themetal ring 15 is locked to the ring stop groove 32.

Furthermore, as shown in FIG. 11, the C-shaped metal ring 15 may beprovided in a ring seating groove 33 formed in the circumferential outersurface of a wedge receiving body 30. In this case, a ring stop groove13 c must be formed in the circumferential inner surface of a bodyseating hole 13.

As such, in the case that the C-shaped metal ring 15 is used as thewedge receiving body support means, it suffices if the C-shaped metalring 15 has a circular or other cross-section, as long as the outersurface or inner surface thereof is rounded.

Meanwhile, a conical wedge seating hole 31, into which the wedge unit 40is seated, is formed in the wedge receiving body 30. The wedge seatinghole 31 has a diameter greater than the diameter of lower ends ofseparated wedge bodies 41 of the wedge unit 40, such that, when theseparated wedge bodies 41 are seated in the wedge seating hole 31, thelower ends thereof protrude outside the wedge seating hole 31.

Furthermore, the edge of the lower end of the wedge receiving body 30that contacts the wedge receiving body support means is preferablyrounded or chamfered, such that, when the tensioning steel wire 50 istensioned, the wedge receiving body 30 elastically expands orplastically deforms a single wedge receiving body support means, whichis provided on the inner surface of the body seating hole 13, or a wedgereceiving body support means, which is provided in a combined manner onthe body seating hole 13 and the wedge receiving body 30, so that thewedge receiving body 30 can be easily moved to the bottom of the bodyseating hole 13. As well, preferably, the wedge receiving body 30 ismade of material that is processed by heat treatment or has stiffnesshigher than that of the first outer body 10.

The wedge unit 40 is seated in the wedge seating hole 31 of the wedgereceiving body 30. The wedge unit 40 includes the three separated wedgebodies 41, which are disposed in a circular arrangement and form a coneshape having a first hole 42, through which the tensioning steel wire 50is inserted. Furthermore, an O-ring 43, which serves to prevent thethree separate wedge bodies 41 from being removed and to expand thediameter of lower ends of the three separate wedge bodies 41, is fittedover circumferential outer surfaces of upper ends of the three separatewedge bodies 41, so that they form a single unit. As well, the upperends of the three separate wedge bodies 41 are closed such that thetensioning steel wire 50 is stopped by the upper ends without passingtherethrough and the lower ends of the three separate wedge bodies 41are expanded in diameter by the O-ring 43.

The first hole 42 of the wedge unit 40 has an uneven inner surface,which has a sawtooth or spiral shape. Therefore, when the tensioningsteel wire 50 is tensioned, the uneven inner surface of the first hole42 serves to prevent the tensioning steel wire 50 from slipping or beingundesirably removed.

It is sufficient for the second outer body 20 to have a structure suchthat the wedge receiving body 30, which is seated in the body seatinghole 13 of the first outer body 10, and the wedge unit 40, which isseated into the wedge seating hole 31 of the wedge receiving body 30,can be securely supported without undesirably moving.

A steel wire tube 51 is watertightly fitted into the tube coupling hole11 of the first outer body 10 without being damaged at an end thereofsuch that it does not interfere with insertion of the tensioning steelwire 50 into the first outer body 10. As well, the steel wire tube 51 isfinished with resin having superior toughness to prevent it frombreaking due to a drop in temperature, so that it can be used even inthe winter. Furthermore, the steel wire tube 51 prevents water fromentering the internal fixer, thus preventing elements of the internalfixer from rusting.

The watertight structure of the steel wire tube 51 includes areinforcing member 52, which is fitted into the end of the steel wiretube 51 inserted into the tube coupling hole 11 of the first outer body10, and a conical watertight packing member 53, which is fitted over theend of the steel wire tube 51, into which the reinforcing member 52 isfitted, and is forcibly fitted into the tube coupling hole 11 of thefirst outer body 10.

Even if the watertight packing member 53 is press-fitted or struck in adirection from the outside of the steel wire tube 51, which is insertedinto the lower end of the first outer body 10, towards the center lineof the steel wire tube 51, the watertight packing member 53 must not bebroken, but must merely be inserted while being plastically deformed.Therefore, the watertight packing member 53 is preferably made of softresin having superior ductility and toughness.

The reinforcing member 52 must be able to prevent a contractionphenomenon of the steel wire tube 51 in which it is reduced in diameterby deformation thereof during a process of forcibly fitting thewatertight packing member 53 into the lower end of the first outer body10 using the compressing force of plastic deformation. To achieve theabove-mentioned purpose, it is preferable that the reinforcing member 52be made of metal or high stiffness material, such as compressed fiberand high stiffness resin.

The assembly of the internal fixer of the present invention having theabove-mentioned construction will be explained herein below. The steelwire tube 51 is first inserted into and coupled to the tube couplinghole 11 of the first outer body 10. Here, after the reinforcing member52 has been fitted into the end of the steel wire tube 51 and theconical watertight packing member 53 has been fitted over the end of thesteel wire tube 51, the end of the steel wire tube 51 is inserted intothe tube coupling hole 11 of the first outer body 10. Thereafter, thewatertight packing member 53 is press-fitted into the tube coupling hole11. Then, the steel wire tube 51 is securely watertightly fitted intoand coupled to the first outer body 10 without being damaged at the endthereof.

In this state, the tensioning steel wire 50 is inserted into the steelwire tube 51, such that the end thereof passes through the body seatinghole 13 of the first outer body 10 and passes through and protrudesoutside the wedge receiving body 30, which is temporarily seated in thebody seating hole 13. Subsequently, the end of the tensioning steel wire50 is maximally inserted into the first hole 42 in the wedge unit 40,which is constructed by assembling the three separated wedge bodies 41with each other using the O-ring 43 such that they are separated in thediameter direction at the lower ends thereof by the O-ring 43.Thereafter, in the state in which the separated wedge bodies 41 areclosed to hold the tensioning steel wire 50, the wedge unit 40 isinserted into the wedge seating hole 31 of the wedge receiving body 30and, thereafter, the second outer body 20 is coupled to the first outerbody 10.

When the second outer body 20 is coupled to the first outer body 10, thesecond outer body 20 pushes the wedge receiving body 30 and theseparated wedge bodies 41 of the wedge unit 40, which is placed in thewedge seating hole 31 of the wedge receiving body 30. Therefore, thewedge receiving body 30 is seated onto the support protrusion 13 a ofthe wedge receiving body support means, and the tensioning steel wire 50is held by the separated wedge bodies 41 more securely.

The internal fixer, which has been assembled through the above-mentionedprocess, is installed in the ground. First, a braced wall is constructedto prevent a cut slope, such as a retaining wall, requiring groundreinforcement, from collapsing. In consideration of the groundreinforcement using anchors, holes are bored downwards at an incline inthe ground to predetermined depths using a boring machine at positionsspaced apart from each other at regular intervals. Thereafter, a grouthose and a load-carrying body, which includes the tensioning steel wireand the internal fixer, are inserted into each boring hole, and grout isinjected through the grout hose. After the injected grout cures with theload-carrying body, an external fixer is coupled to the other end of thetensioning steel wire, which is adjacent to the braced wall.

In this state, the tensioning steel wire is pulled by a tensioningmachine, so that the grout and ground are tensioned, thus reinforcingthe soft ground. This will be explained in detail with reference toFIGS. 1 and 3.

When the tensioning steel wire is pulled at a position adjacent to thebraced wall, the tensile force of the tensioning machine is transmittedto the wedge receiving body 30 through the wedge unit 40. Thus, thewedge receiving body 30 along with the wedge unit 40 is advanced afterbreaking the support protrusion 13 a, which is provided on the innersurface of the body seating hole 13 of the first outer body 10, untilthe wedge receiving body 30 reaches the bottom of the body seating hole13 of the first outer body 10, that is, until it changes from the stateof FIG. 1 to that of FIG. 3. At this time, because the wedge unit 40 isin a state of being tensioned by the tensioning steel wire 50, the wedgereceiving body 30 maintains the state of being seated in the wedgeseating hole 31. Therefore, the separated wedge bodies 41 of the wedgeunit 40 reliably hold the tensioning steel wire 50.

As such, when the wedge receiving body 30 is advanced until it reachesthe bottom of the body seating hole 13 of the first outer body 10, thewedge receiving body 30 is securely fastened to the body seating hole 13of the first outer body 10 by the broken support protrusion 13 a, whichhas been provided on the inner surface of the body seating hole 13 ofthe first outer body 10, as if it were processed by being integrated orpress-fit.

Continuously, as the tensioning machine more strongly pulls thetensioning steel wire 50, increased tensile force is applied to thegrout, the ground and the tensioning steel wire 50. Meanwhile, after theground reinforcing work has been completed, the tensioning steel wire 50must be removed.

In the process of removing the tensioning steel wire 50, the part of thetensioning steel wire 50 exposed outside at a side adjacent to thebraced wall is first cut using an oxygen cutting machine to remove thetensile force, which has been applied to the tensioning steel wire 50.At this time, in the state in which the wedge receiving body 30 isfastened in the body seating hole 13 of the first outer body 10, thewedge unit 40 may be slightly moved backwards by repulsive forcegenerated when removing the tensile force from the tensioning steel wire50.

Thereafter, the cut end of the tensioning steel wire 50, part of whichis installed in the ground, is struck with a hammer one or two times.Then, as shown in FIG. 4, only the wedge unit 40 is moved backwards bythe force of striking the tensioning steel wire 50, and the separatedwedge bodies 41 are separated in the diameter direction by the O-ring43. Therefore, the tensioning steel wire 50 is released from theseparated wedge bodies 41 of the wedge unit 40.

As such, the reason why the wedge unit 40 can be moved backwards isthat, when the tensioning steel wire 50 is tensioned, a space is definedbehind the wedge unit 40 by movement of the wedge receiving body 30 andthe wedge unit 40 to the bottom of the body seating hole 13 of the firstouter body 10.

As such, after the tensioning steel wire 50 has been released from thewedge unit 40, because the only resistance is its own weight and alittle frictional resistance, the tensioning steel wire 50 can be easilyremoved by pulling it.

FIG. 12 is a sectional view showing an internal fixer for an anchorhaving a releasable tensioning steel wire, a wedge returning means beingprovided for a wedge unit, according to another embodiment of thepresent invention. In the wedge returning means, a spring seating hole17 is formed in the bottom of a body seating hole 13 of a first outerbody 10, and a wedge returning member 60 is provided in the springseating hole 17, such that, when the tensioning steel wire 60 istensioned so that a wedge receiving body 30 is advanced into andfastened into a body seating hole 13, ends of separated wedge bodies 41of the wedge unit 40 which protrude from the wedge seating hole 31 ofthe wedge receiving body 30 are biased backwards by the wedge returningmember 60.

The wedge returning member 60 is not limited to any particularstructure, so long as it can push the end of the wedge unit 40 backwardsand can be inserted into the wedge seating hole 31 of the wedgereceiving body 30. Preferably, a compression coil spring is used as thewedge returning member 60. The shape of the compression coil spring maybe changed depending on the size of the spring seating hole 17.

For example, in the case that the diameter of the spring seating hole 17is about twice that of the tensioning steel wire, it is preferable thata conical compression coil spring be used. In the case that the springseating hole 17 has a relatively small diameter similar to that of thewedge seating hole 31, it is preferable that a cylindrical compressioncoil spring be used.

As described above, in the case that the wedge returning member 60 isprovided in the internal fixer of the present invention, in a process ofremoving the tensioning steel wire 50 after the ground reinforcing workhas been completed, when the part of the tensioning steel wire 50 thatis exposed outside at the side adjacent to the braced wall is cut usingan oxygen cutting machine to remove the tensile force, which has beenapplied to the tensioning steel wire 50, the wedge unit 40 is easilymoved backwards both by repulsive force, which is generated upon removalof the tensile force of the tensioning steel wire 50 in the state inwhich the wedge receiving body 30 is fastened in the body seating hole13 of the first outer body 10, and by restoring force of the compressioncoil spring, which is the wedge returning member 60, as shown from FIG.13 to FIG. 14.

Here, even if the wedge unit 40 is not moved backwards for some reasonsuch as corrosion of the wedge receiving body 30 and the wedge unit 40,when the cut end of the tensioning steel wire 50, part of which isinstalled in the ground, is struck with a hammer one or two times, asshown in FIG. 15, the wedge unit 40 can be moved backwards both by theforce of striking the tensioning steel wire 50 and by the restoringforce of the compression coil spring, which is the wedge returningmember 60.

As such, when the wedge unit 40 is moved backwards so that the separatedwedge bodies 41 are separated in the diameter direction by an O-ring 43,the tensioning steel wire 50 is released from the separated wedge bodies41 of the wedge unit 40. Therefore, the tensioning steel wire 50 can beeasily removed by pulling it.

Meanwhile, as shown in FIG. 16, the wedge returning member 60 mayconsist of a support ring member 61, which supports the ends of theseparated wedge bodies 41 and has a flange on an end thereof, and acompression coil spring 62, which has a cylindrical shape and pushes thesupport ring member 41 backwards.

FIG. 17 illustrates an internal fixer for an anchor having a releasabletensioning steel wire, a wedge support means being provided for a wedgeunit, according to another embodiment of the present invention. In thisembodiment, the second outer body 20 has a length sufficient to define aspace for ensuring backward movement of a wedge unit 40. An elasticsupport member 70, which pushes and seats the wedge unit 40 into a wedgeseating hole 31 of a wedge receiving body 30, is installed in the spacedefined in the second outer body 20. The elastic support member 70 isnot limited to any particular structure, so long as it elastically andreliably supports the wedge unit 40. Preferably, a cylindrical orconical compression coil spring, which is freely available, is used asthe elastic support member 70.

To assemble this embodiment having the above-mentioned construction, thewedge receiving body 30 along with the wedge unit 40 is seated into abody seating hole 13 of a first outer body 10. Thereafter, the secondouter body 20 is coupled to the first outer body 10 after the elasticsupport member 70 has been installed in the second outer body 20. Then,the wedge unit 40 is elastically supported by the elastic support member70.

Furthermore, to assemble the tensioning steel wire 50, the tensioningsteel wire 50 is inserted into a steel wire tube 51, which is fittedinto a tube coupling hole 11 of the first outer body 10. Then, the wedgeunit 40 is moved backwards from the wedge receiving body 30 by thetensioning steel wire 50 in the state of being elastically supported bythe elastic support member 70, so that the separated wedge bodies 41 ofthe wedge unit 40 are separated in the diameter direction by an O-ring43 while an end of the tensioning steel wire 50 is inserted into theseparated wedge bodies 41.

Thereafter, when force, which has been applied to the tensioning steelwire 50, is removed in the state in which the tensioning steel wire 50is inserted into the separated wedge bodies 41, the separated wedgebodies 41 are inserted into the wedge seating hole 31 of the wedgereceiving body 30 by the restoring force of the elastic support member70. At this time, the tensioning steel wire 50 is reliably held by theseparated wedge bodies 41. As such, the assembly of the tensioning steelwire 50 can be more easily conducted.

FIG. 18 illustrates an internal fixer for an anchor having a releasabletensioning steel wire, a wedge support means being provided for a wedgeunit, according to another embodiment of the present invention. In thisembodiment, an inner ring groove 43 is formed in an upper end of a firsthole 42 defined by separated wedge bodies 41. A cap member 45, which isprovided with a flange and has a cap-shaped cross-section, is coupled tothe inner ring groove 43 and protrudes from the upper end of the firsthole 42 without interfering with the diameter expanding motion of theseparated wedge bodies 41. Even in this case, in which the cap member 45protrudes from the upper end of the separated wedge bodies 41, anelastic support member 70, which pushes and seats the wedge unit 40 intoa wedge seating hole 31 of a wedge receiving body 30, is provided in thesecond outer body 20. Although the wedge support means has beenexplained as having only a structure such that the cap member 45 iscoupled to the inner ring groove 43 of the wedge unit 40, a circularplate may be additionally provided.

According to this embodiment having the above-mentioned construction,because the elastic support member 70, which comprises the cylindricalor conical compression coil spring, is seated onto the wedge unit 40 andfitted over the outer surface of the cap member 45, which protrudes fromthe wedge unit 40, operational precision is ensured without the elasticsupport member 70 being misaligned or undesirably moving.

Particularly, the end of the tensioning steel wire 50, which is insertedthrough a tube coupling hole 11 of the first outer body 10, is disposedin the cap member 45 via the separated wedge bodies 41. Thus, thetensioning steel wire 50 is reliably held by the separated wedge bodies41. Furthermore, because the separated wedge bodies 41 hold thetensioning steel wire 50 more strongly, the tensioning steel wire 50,which is formed by twisting several wires, may be untwisted at a partthereof that is in the cap member 45, so that the diameter of that partof the tensioning steel wire 50 is slightly increased. Therefore, thetensioning steel wire 50 can be more securely held, as if a stopprotrusion were formed on the tensioning steel wire 50.

Furthermore, as shown in FIG. 19, a compression cover 71 may is seatedon the separated wedge bodies 41 outside the cap member 45 between theseparated wedge bodies 41 and the elastic support member 70. Thecompression cover 71 prevents interference between the separated wedgebodies 41 and the elastic support member 70 and makes it possible forthe separated wedge bodies 41 to be reliably separated in the diameterdirection when being moved away from the wedge seating hole 31 of thewedge receiving body 30 during a process of assembling the tensioningsteel wire 50, thus making the assembly of the tensioning steel wire 50rapid and precise.

INDUSTRIAL APPLICABILITY

As described above, an internal fixer for an anchor having a releasabletensioning steel wire according to the present invention can beefficiently used in engineering work, in which holes are bored at apredetermined position in soft ground using a boring machine, a grouthose and a load-carrying body, which includes the tensioning steel wireand the internal fixer, are inserted into the boring hole, grout isinjected through the grout hose, the injected grout cures with theload-carrying body, an external fixer is coupled to the other end of thetensioning steel wire, and the tensioning steel wire is pulled by atensioning machine so that the grout and ground are tensioned, thusreinforcing the soft ground. That is, the present invention can be usedin engineering work such as bracing work and engineering work forstabilizing a tunnel portal or for reinforcing a stone wall or aretaining wall.

1. An internal fixer for an anchor having a releasable tensioning steelwire, comprising: a first outer body (10), with a tube coupling hole(11) and a body seating hole (13) coaxially formed in the first outerbody (10) so that the tensioning steel wire (50) passes therethrough,and wedge receiving body support means provided on an inner surface ofthe body seating hole (13); a wedge receiving body (30) seated by thewedge receiving body support means in the body seating hole (13) andhaving a conical wedge seating hole (31), into which separated wedgebodies (41) are seated; a wedge unit (40) seated into the wedge seatinghole (31) of the wedge receiving body (30) and comprising the threeseparated wedge bodies (41), which are arranged in a cone shape to holdthe tensioning steel wire (50); and a second outer body (20) supportingand covering both the wedge receiving body (30), which is seated in thebody seating hole (13) of the first outer body (10), and the wedge unit(40), which is placed in the wedge seating hole (31) of the wedgereceiving body (30).
 2. An internal fixer for an anchor having areleasable tensioning steel wire, comprising: a first outer body (10),with a tube coupling hole (11) and a body seating hole (13) coaxiallyformed in the first outer body (10) so that the tensioning steel wire(50) passes therethrough, and wedge receiving body support meansprovided on an inner surface of the body seating hole (13); a wedgereceiving body (30) seated by the wedge receiving body support means inthe body seating hole (13) and having a conical wedge seating hole (31),in which separated wedge bodies (41) are seated; a wedge unit (40)seated into the wedge seating hole (31) of the wedge receiving body (30)and comprising the three separated wedge bodies (41), which are arrangedin a cone shape to hold the tensioning steel wire (50); a second outerbody (20) supporting and covering the wedge receiving body (30), whichis seated in the body seating hole (13) of the first outer body (10);and an elastic support member (70) provided in the second outer body(20) and elastically supporting, pushing and seating the wedge unit(40), which is placed in the wedge seating hole (31) of the wedgereceiving body (30), into the wedge seating hole (31).
 3. The internalfixer for the anchor having the releasable tensioning steel wireaccording to claim 1 or 2, wherein the wedge receiving body supportmeans of the first outer body (10) along with the second outer body (20)supports the wedge receiving body (30) while no tensile force is appliedto the tensioning steel wire (50), and the wedge receiving body supportmeans allows the wedge receiving body (30) to be advanced along with thewedge unit (40) and to be fastened when tensile force is applied to thetensioning steel wire (50) after the internal fixer is installed inground.
 4. The internal fixer for the anchor having the releasabletensioning steel wire according to claim 3, wherein the wedge receivingbody support means comprises a support protrusion (13 a) provided on theinner surface of the body seating hole (13).
 5. The internal fixer forthe anchor having the releasable tensioning steel wire according toclaim 3, wherein the wedge receiving body support means is realized by atapered inner surface of the body seating hole (13) which decreases indiameter from a deep portion thereof to a shallow portion thereof. 6.The internal fixer for the anchor having the releasable tensioning steelwire according to claim 4 or 5, wherein the tapered inner surface of thebody seating hole (13) and the support protrusion (13 a), which isprovided on the inner surface of the body seating hole (13), are formedin ring shapes around an entire circumference of the body seating hole(13).
 7. The internal fixer for the anchor having the releasabletensioning steel wire according to claim 4 or 5, wherein the taperedinner surface of the body seating hole (13) and the support protrusion(13 a) respectively comprise a plurality of tapered inner surfaces ofthe body seating hole (13) and a plurality of support protrusions (13a), which are provided on the inner surface of the body seating hole(13) and are spaced apart from each other.
 8. The internal fixer for theanchor having the releasable tensioning steel wire according to claim 4,wherein the support protrusion (13 a) of the body seating hole (13) ismulti-stepped.
 9. The internal fixer for the anchor having thereleasable tensioning steel wire according to claim 3, wherein the wedgereceiving body support means comprises a support O-ring (14) provided ina ring groove (13 b) formed in the inner surface of the body seatinghole (13), such that, when the wedge receiving body (30) is advanced bythe tensioning steel wire (50), the support O-ring (14), which hassupported an end of the wedge receiving body (30), comes into closecontact with and holds an outer surface of the wedge receiving body(30).
 10. The internal fixer for the anchor having the releasabletensioning steel wire according to claim 3, wherein the wedge receivingbody support means comprises a C-shaped metal ring (15), whichelastically expands in diameter and is provided in a ring groove (13 b)formed in the inner surface of the body seating hole (13), such that,when the wedge receiving body (30) is advanced by the tensioning steelwire (50), the C-shaped metal ring (15), which has supported an end ofthe wedge receiving body (30), holds an outer surface of the wedgereceiving body (30).
 11. The internal fixer for the anchor having thereleasable tensioning steel wire according to claim 10, wherein a ringstop groove (32) is formed in the outer surface of the wedge receivingbody (30), such that, when the wedge receiving body (30) is advanced,the metal ring (15) is locked to the ring stop groove (32).
 12. Theinternal fixer for the anchor having the releasable tensioning steelwire according to claim 10 or 11, wherein the wedge receiving bodysupport means comprises: the C-shaped metal ring (15) provided in a ringseating groove (33) of the wedge receiving body (30); and a ring stopgroove (13 c) formed in the inner surface of the wedge seating groove(13).
 13. The internal fixer for the anchor having the releasabletensioning steel wire according to claim 1 or 2, further comprising: awedge returning member (60) provided in the body seating hole (13) ofthe first outer body (10), so that, when the wedge receiving body (30)along with the wedge unit (40) is advanced and fastened to the bodyseating hole (13), the wedge unit (40), which is placed in the wedgeseating hole (31) of the wedge receiving body (30), is biased backwardsby the wedge returning member (60).
 14. The internal fixer for theanchor having the releasable tensioning steel wire according to claim13, wherein the wedge returning member (60) comprises a compression coilspring.
 15. The internal fixer for the anchor having the releasabletensioning steel wire according to claim 13 or 14, further comprising: asupport ring member (61), having a flange on an end thereof, provided onan end of the wedge returning member (60) to support lower ends of theseparated wedge bodies (41).
 16. The internal fixer for the anchorhaving the releasable tensioning steel wire according to claim 13 or 14,wherein a spring seating hole (17) is formed in a bottom of the bodyseating hole (13) so that the wedge returning member (60) is installedin the spring seating hole (17), and a support protrusion (17 a) isprovided on a bottom of the spring seating hole (17) to hold an end ofthe wedge returning member (60).
 17. The internal fixer for the anchorhaving the releasable tensioning steel wire according to claim 2,further comprising: a cap member (45) fitted into an inner ring groove(43) formed in upper ends of the separated wedge bodies (41)constituting the wedge unit, so that an elastic support member (70) isfitted over the cap member (45) and the tensioning steel wire (50) isinserted more deeply.
 18. The internal fixer for the anchor having thereleasable tensioning steel wire according to claim 2 or 17, wherein theelastic support member (70) comprises a compression coil spring fittedover an outer surface of the cap member (45), which protrudes from theupper end of the wedge unit (40), without moving.
 19. The internal fixerfor the anchor having the releasable tensioning steel wire according toclaim 2 or 17, further comprising: a compression cover (71) providedbetween the separated wedge bodies (41) and the elastic support member(70) and seated on the separated wedge bodies (41) outside the capmember (45).